For any person, there are two types of things he does in life. One, that what he wants to do. And two, that he needs to do. Prioritizing between them defines the gesture of that person.
To understand what he wants to do, he has to know his passions. And to understand what he needs to do, he has to know his responsibilities.
When it's time for him to decide between these two, what he ultimately does revelas his way of prioritizing people in his life. Whatever he chooses, that's nothing wrong on his side, he might be right in many of his ways and thoughts. He just needs to be understood more, if you think his is a wrong choice.